The existing touch panel device, also known as a touch screen, is an induction-type liquid crystal display (LCD) device able to receive input signals from contact points. The induction-type liquid crystal display device generally includes two layers: an upper layer and a lower layer. The lower layer is a traditional LCD display panel, and the upper layer is a transparent touch-sensitive screen. When a physical contact is made with the transparent screen, its touch feedback system can be pre-programmed to drive a variety of software programs or hardware. The transparent touch-sensitive screen often includes a capacitive screen type and a resistive screen type. Further, the capacitive screen type can use a so-called projected capacitive touch technology.
A projected capacitive touch screen can be further divided into two types: a self capacitance screen and a mutual capacitance screen. In a self capacitance screen, two electrode layers made with Indium tin oxide (ITO) are formed over the surface of the screen glass into horizontal and vertical electrode arrays. Each of the horizontal electrode array and the vertical electrode array has certain capacitance with respect to the ground. This capacitance is referred as self-capacitance, the capacitance between the electrode array and the ground. When a finger touches the screen, the finger's capacitance will be added to the self capacitance of the screen, so that the capacitance of the screen increases. The changes in the capacitance can be detected and the touch point position can be determined.
A mutual capacitance screen is also produced by forming two ITO electrode layers over the surface of the screen glass, as horizontal and vertical electrode arrays. The mutual capacitance screen differs from the self capacitive screen in that the capacitance of the mutual capacitance screen is the capacitance between the horizontal electrode array and the vertical electrode array. That is, the horizontal electrode array and the vertical electrode array are two layers of a capacitor of the mutual capacitance screen. When a finger touches the capacitive screen, the touch impacts the coupling between the two electrode layers, and thus changes the capacitance between the two electrode layers. The changes in capacitance can be detected and the touch point position can be determined.
A resistance touch screen often has a hard coating surface to protect an underlying polyester film (PET) layer. Between the hard coating surface and a glass substrate, there are two layers of transparent conductive ITO respectively corresponding to the X-axis and the Y-axis. The two layers of ITO are insulated by transparent fine particles. When a finger touches the screen, the pressure from the touch causes a connection of the two conductive layers at the touch point. Different touch points correspond to different output resistances from the touch points. An output voltage corresponding to a position of the touch point can thus be obtained (in an analog format), and the voltage is further A/D converted to derive the X and Y coordinates of the touch point.
Thus, conventional touch screen technologies generally require a touch-sensitive transparent screen on top of a display screen. The touch-sensitive transparent screen is often attached to the display screen using optical glue. However, the production process of this type of layered touch screen is often troublesome due to strict manufacturing process requirements, and thus may substantially increase the production cost of the layered touch screens. Further, by adding the extra transparent touch-sensitive layer, the thickness and weight of the touch screen can also be increased.
The disclosed methods and systems are directed to solve one or more problems set forth above and other problems.